The subject matter disclosed herein generally relates to structural health monitoring systems, and more particularly to self-powered multi-functional health monitoring sensors.
Vibration-based structural health monitoring has been increasingly employed in high speed rotational machineries for both operational and health condition monitoring, including damage detection. Vibration-based detection of faulty conditions of the machines or structures has been repeatedly demonstrated with conventional accelerometers successfully.
Current damage detection sensors may rely on piezoelectric materials such as piezoelectric transducers (PZTs) bonded to a structure. For example, a first PZT is excited at high frequencies. A second, nearby PZT sensor measures a response of the structure due to excitation by the first PZT sensor. Any structural damage present in the path between the two PZT actuator/sensors is indicated by changes in the frequency response function (“FRF”) relative to its baseline. In this approach, the PZT actuator/sensor is used solely for the purpose of excitation and damage detection at very high operating frequencies.
The PZTs are connected, electrically, to signal conditioning and/or data collection and data processing or similar devices, which require power sources. Traditional structural health monitoring systems employing PZTs thus include external or separate power sources and associated wiring connecting the PZTs to the external power sources. Further, communication lines and/or wiring may add to the bulk of the system.